Donnelly takes big lead over Mourdock

11/2/12 7:47 AM EDT

Democratic Rep. Joe Donnelly has jumped to a double-digit lead over Republican Richard Mourdock in the Indiana Senate race, a development that makes the GOP climb to the majority even steeper.

A new Indiana Battleground Poll, conducted for Howey Politics Indiana and DePauw University, found Donnelly up 47-36 percent, with Libertarian candidate Andrew Horning pulling 6 percent of the vote. Donnelly's 11-point lead is a huge increase from the 2-point advantage that the same poll showed him holding in September.

The results strongly suggest that Mourdock's support has eroded after his controversial remarks last week that God intended for pregnancies to occur after rape. The GOP has been spending big to save his candidacy, with outside groups pouring in about $4 million in just the last week alone.

The Mourdock campaign is downplaying the numbers and released an internal poll Friday morning showing the Republican up 2 points over Donnelly.